Tertiary tectonics of the Hispaniola Fault Zone in the northwestern peidmont of the Cordillera Central, Dominican Republic

The Hispaniola Fault Zone (HFZ) separates the Cordillera Central from a piedmont in the west-central region of the Dominican Republic. The HFZ is part of a 250-km wide plate boundary zone known as the Northern Caribbean Plate Boundary Zone. This active zone of tectonic deformation separates the North American and Caribbean plates. New structural mapping within the piedmont zone, a dissected plateau that separates the Cordillera from the Cibao Valley, reveals strike-slip faulting began as early as the Oligocene and has continued until at least the late Miocene. Strike-slip faulting along the piedmont is responsible for creating a pull-apart basin. En echelon patterns of parallel and oblique faults cutting the piedmont have resulted in thick deposits of clastic rocks eroded from the Cordillera. In addition, carbonate reefs and reworked sediments can be found. Most of the sedimentary units have faulted boundaries with each other. Their complex geometries, including both dip-slip and strike-slip faulting as well as folding, can be explained by a Riedel model. The study area is bounded by the coordinates 70°45′ W to 71°15′W and 19°30′ N to 19°20′N within the San José de las Matas and Monción quadrangles of the piedmont. New road-cuts and a dam project within the study area create a unique opportunity to produce a new, 1:50,000 scale geologic map. Folding and faulting within the pull-apart basin are consistent with regional deformation and the tectonic evolution of the North American/Caribbean plate boundary.